0166: Effect of Air Pollution on Prevalence and Disease Activity of Rheumatoid Arthritis in the German Middle-aged Population from the NAKO Baseline Examination

Background/Purpose: Environmental influences affect the human body throughout life, from conception to old age. The influence of air pollution and fine dust particles on systemic diseases, particularly rheumatoid arthritis (RA), has been studied in various regions, but has not yet been comprehensively recorded for Germany. Therefore, the aim of this study is to describe the associations between air pollution and the prevalence and disease activity of RA in Germany.

Methods: In the German National Cohort (NAKO) Health Study, medical histories and examination findings were collected from a total of 204,729 individuals (18-69 years of age) in a population sample from 18 study centers between 2014 and 2019. In addition, 23,456 individuals underwent a clinical hand examination of 20 joints for pain and swelling by trained examiners (Level 2 subcohort), enabling the calculation of DAS28 as a measure of rheumatic disease activity. Cumulative and daily air pollution levels were made available for the NAKO study regions by the Environmental Data Unit in Munich (air pollutants (UBA: particulate matter particle size (PM) 2.5, PM10, nitrogen oxide (NO2), and ozone (O3)) to the nearest 1 km from the place of residence on a daily basis; air pollutants (ELAPSE: PM2.5, NO2, O3, black carbon (BC)) to the nearest 100 m for 2010. The analyses were adjusted for age, sex, smoking status, BMI, and income.

Results: RA was known in 4033 individuals of the total cohort (1.97%) and 426 individuals (1.82%) of the Level 2 cohort. Disease activity in the cohort was low (mean DAS28 1.37, standard deviation 1.03). The occurrence of RA was positively associated with age (10-year OR = 1.65 [95% CI: 1.59-1.71]) and female sex (OR = 2.67 [2.46-2.90]). Individuals with RA were on average 57 years old (vs. 50 years old in those without RA), and 71% were female (50%). 39% (vs. 44%) reported never smoking, 36% (vs. 32%) reported previously smoking, and 18% (vs. 20%) were currently smoking.

The historical (ELAPSE) and daily (UBA) environmental pollution levels of the respective place of residence showed a strong association with DAS28. Fine dust particle pollution for PM2.5 and PM10, NO2, and BC were positively associated with RA disease activity. In contrast, ozone pollution showed a negative association with disease activity. There was no clinically relevant effect of particulate matter pollution on the frequency of RA for PM2.5 and PM10, NO2, and BC for either the current or historical measurements, although the frequency was lower at higher ozone levels.

Conclusion: A clinically relevant association of disease activity with all air pollutant exposures for RA was demonstrated in the population sample of over 200,000 individuals. However, a relevant association between air pollutant exposure at the current place of residence and the occurrence of RA could not be demonstrated. The cross-sectional results presented here will also be prospectively examined in the NAKO cohort for 20 years to provide stronger conclusions regarding causality, particularly with regard to the different frequencies observed in the study centers.